/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.coyote.http11.filters;

import org.apache.coyote.OutputBuffer;
import org.apache.coyote.Response;
import org.apache.coyote.http11.OutputFilter;
import org.apache.tomcat.util.buf.ByteChunk;

import java.io.IOException;

/**
 * Identity output filter.
 *
 * @author Remy Maucherat
 */
public class IdentityOutputFilter implements OutputFilter {


	// ----------------------------------------------------- Instance Variables

	/**
	 * Content length.
	 */
	protected long contentLength = -1;

	/**
	 * Remaining bytes.
	 */
	protected long remaining = 0;

	/**
	 * Next buffer in the pipeline.
	 */
	protected OutputBuffer buffer;


	// --------------------------------------------------- OutputBuffer Methods

	/**
	 * Write some bytes.
	 *
	 * @return number of bytes written by the filter
	 */
	@Override
	public int doWrite(ByteChunk chunk, Response res)
			throws IOException {

		int result = -1;

		if (contentLength >= 0) {
			if (remaining > 0) {
				result = chunk.getLength();
				if (result > remaining) {
					// The chunk is longer than the number of bytes remaining
					// in the body; changing the chunk length to the number
					// of bytes remaining
					chunk.setBytes(chunk.getBytes(), chunk.getStart(),
							(int) remaining);
					result = (int) remaining;
					remaining = 0;
				} else {
					remaining = remaining - result;
				}
				buffer.doWrite(chunk, res);
			} else {
				// No more bytes left to be written : return -1 and clear the
				// buffer
				chunk.recycle();
				result = -1;
			}
		} else {
			// If no content length was set, just write the bytes
			buffer.doWrite(chunk, res);
			result = chunk.getLength();
		}

		return result;

	}

	@Override
	public long getBytesWritten() {
		return buffer.getBytesWritten();
	}


	// --------------------------------------------------- OutputFilter Methods

	/**
	 * Some filters need additional parameters from the response. All the
	 * necessary reading can occur in that method, as this method is called
	 * after the response header processing is complete.
	 */
	@Override
	public void setResponse(Response response) {
		contentLength = response.getContentLengthLong();
		remaining = contentLength;
	}

	/**
	 * Set the next buffer in the filter pipeline.
	 */
	@Override
	public void setBuffer(OutputBuffer buffer) {
		this.buffer = buffer;
	}

	/**
	 * End the current request. It is acceptable to write extra bytes using
	 * buffer.doWrite during the execution of this method.
	 */
	@Override
	public long end()
			throws IOException {

		if (remaining > 0)
			return remaining;
		return 0;

	}

	/**
	 * Make the filter ready to process the next request.
	 */
	@Override
	public void recycle() {
		contentLength = -1;
		remaining = 0;
	}
}
